THIS invention relates to a tracking assembly of the type adapted to track the alignment of belts and webs. The invention will be described with particular reference to a tracking roller for tracking conveyor belts, but it is to be understood that the invention can be used in a number of different applications such as the tracking of other belts, webs, sheets, lengths of cloth, and the like.
Tracking rollers are known and one roller which has proved to be particularly effective in practice is that described in applicants PCT patent no. PCT/AU95/00618. The specification of that patent is incorporated herein by way of reference. The tracking roller described in patent no. PCT/AU95/00618 has proved to be particularly effective for tracking of conveyor belts, particularly belts up to about 1200 mm wide. Belts wider then that tend to cause failure of the shaft which carries the drum due to the high bending moment which is induced into the centre of the shaft at the pivot point of the roller.
The specification of patent no. PCT/AU95/00618 describes only the tracking of flat belts. However, trough shaped conveyor belts and V-shaped return belts are used in many installations and the applicant has found that certain of the principles described in patent no. PCT/AU95/00618 can surprisingly be utilised for the tracking of non-flat belts.
According to the invention there is provided a tracking assembly for tracking belts and webs comprising:
a support frame adapted to be mounted below a travelling belt or web;
a generally elongate support shaft pivotally mounted about its centre to the frame and pivotable relative to the frame about a generally vertical pivot axis;
a roller mounted cantilever fashion to each end of the shaft, each roller being rotatable about an axis which is coincident with the shaft axis, the two rollers being adapted to support said travelling belt or web;
each of the rollers having a reduced diameter end region on the distal end thereof which, when either one of said end regions is contacted by a belt or web travelling off-centre will cause the shaft to pivot relative to the support frame and thereby steer the belt or web back to a centralized position.
The shaft may be straight or may be of V-shaped configuration.
Preferably the elongate support shaft has a stop means associated therewith adapted to limit the pivotal rotation of the shaft relative to the frame through a selected pivotal arc. The stop means may be adjustable in order to vary the pivotal arc through which the shaft is able to pivot.
These and further features of the invention will be made apparent from the description of an embodiment thereof given below by way of example. In the description reference is made to the accompanying drawings but the specific features shown in the drawings should not be construed as limiting on the invention.